Sheet metal spinning machine



April 6, 1954 D. J. GRIFFIN SHEET METAL SPINNING MACHINE Filed April 23, 1949 oEwY J. GRIFFI Patented Apr. 6, 1354 UNITED STATES PATENT OFFICE 2,674,216- sHEET METAL SPINNING MACHINE Dewey J. Griiin, Wichita, Kans. Application April z3, 1949, serial No. 89,230

:il claims. (ci. 11s-52) This invention yrelates to machines for forming sheet metal blanks intoshape's having a desired outer contour by the process commonly known as spinning In this process a substantially tubular sheet metal blank is positioned and held on a heavy drum, which serves as a female die, and which has an outer contour of a desired shape. The drum is then rotated slowly and a hard smooth tool is pressed against the outer surface of the sheet metal blank, thus forcing the metal to conform to the shape of the drum, or die.

Usually the hard smooth tool is handled manually. The manual handling of such a tool causes fatigue, and the element of human error due to poor muscular coordination, or to fatigue, or both, often results in a very poor spinning job. To do the job properly it is desirable that the tool be moved slowly in an axial direction along the outer surface of the drum, thus causing pressure to be applied to the sheet metal blank in a continuous spiral. If the convolutions of this spiral are not spaced very close together, or if they are irregularly spaced, then a poor forming job is produced, and extensive sanding and polishing is required, thus greatly increasing the over all cost of production.

It is the chief object of this invention to provide a. spinning machine which will eliminate this element of human error by including a power rotated screw adapted to cooperate with a vspinning tool to hold such tool at the proper angle with relation to the work, and to cause such tool to traverse the work at a selected speed in either direction.

It is another object to provide a means for varying the angular relationship between the rotational axes of the screw and of the spinning drum, thus making it possible to keep the spinning tool at a desired angle with relation to the surface being worked upon.

Another object is to provide a new type of spinning tool for cooperation with a power rotated screw for moving the tool with relation to the work.

The invention, together with other objects attending its production, will be more clearly understood when the following description Vread in connection with the accompanying illustrative drawings, in which:

Fig. 1 is atop plan view of a spinning machine embodying the invention;`

Fig. 2 is a side View of the same machine;

Fig. 3 is a perspective View of a spinning tool constituting a part of the invention;

Fig. 4 is a fragmentary perspective view illustrating certain details of construction of themachine ;v

Fig. 5 i's a sectionalvi'ew taken along the'line 5-5 of Fig". l, butalso includes a portion of a metal working tool in side` elevation; and

Fig. 6 is a perspectivek view of one part of the machine illustrated in Figs. 1 and 2.

Referring to Figs. 1 and 2 the machine includes a rigid horizontal frame made up of -beam frame members I0, II, I2,'I3, I4, I5, and I6 supported on a. suitable plurality of upright legs 21 and 28. The frame members I0, II, and I3 carry bearing blocks I1, I8, and I9, for drum shaft 20. It will be noted that the bearing I9 is in reality only a half bearing-a cradle type bearing. Thus the frame member I3 can be moved outwardly from the shaft to permit a sheet metal blank to be slipped onto a spinning drumy or die 2l, carried on the shaft. The details oi this frame arrangement are not essential to this invention. and have therefore been purposely omitted.

The shaft 20 is power rotated by means of an electric motor 22, driving a variable speed transmission 23 by means of a belt 24, power being transmitted from the transmission 23 to the shaft 26 through a universal joint 25. The motor is supported on the frame member I5, While the transmission is mounted on a horizontal plate 26 welded to the frame member I0.

An elongated auxiliary frame member 23 has one of its ends pivotally connected to the frame member I4 by means of a suitable pivot pin 30. The opposite end of this auxiliary frame member 29 is supported by and is slidable on the frame members I0 and IIE.

A rigid plate 3I has one' end welded to an end of the frame member I I in the position shown in Figs. 1 and 2. The other end of the plate 3| pivotally supports the shank 32 of an internally threaded socket 33 (see Fig. 6). The socket 33 receives and supports a threaded screw 3d pro vided at its outer end with a hand wheel 35. The opposite end of the screw 34 is reduced in diameter (see Fig. 5) and passes loosely through a short slot in the web of the I-beam 23. A convex surface nut 36 is held in position on the reduced end of the screw as shown, by means of a lock nut 31. With the arrangement described, the auxiliary framev member 23 can be pivoted in either direction aboutV its pivot point 36 simply by rotating the screw 34'. Thus the position of the frame member 29 can be' changed with relation to the surface of the drum or die 2 I.

On the free end of the member 29 a. motor 33 is mounted.l Through a belt or chain 39 the motor drives a reversible variable speed transmission 40, which in. turn rotates a threaded shaft 4I through a universal joint 42. The shaft is rotatably supported on. the frame member 29 by means of bearingblocks 43,r 44, and 45', andl by intermediatel lquarterj" bearing blocks 4B and 41. other views of such blocksv being vshown in Figs. 4 and 5. 'I'hese blocks 46 and 47 contact unthreaded portions of the shaft 4|, as shown, and support the shaft against lateral movement away from the drum 2|. They also permit uninterrupted travel .of v aspinningftool (Fig. 3) along the threaded portion ofthe shaft 4| between the bearing blocks 44 and 45.

A preferred form of spinning tool is illustrated in Fig. 3. It includes a rigid plate 42h-threaded half-nuts 49 and 50 welded to theunder side of this plate in spaced alignment, and made to complementally fit and ride von the threaded portions of the shaft 4|; a metal block 5| in the form of a saddle, welded on the upperk surface of the plate 48; a heavy'V rod or tube 52 adapted tobe received by the saddle and held in a position substantially at right anglesto the axis of said half-nuts; a removable strap 53 anchored to the saddle by studs 54, and adapted to hold the rod 52 against longitudinal and rotative movement with relation to the saddle; a polished sheet metal working nose 55 of tool steel rigidly mounted on one end of the rod 52, the working surface having a rounded contour, as shown; and a removable handle extension 56 having a socket 51 for receiving the opposite end of the rod 52, and a set screw 58 for holding the rod end in position in the socket.

It should be noted that the rod 52 and its metal work nose 55 are made as a unit, and that units having various shaped noses are required for performing the various spinning operations in cooperation with the surfaces of different shaped drums or dies.

Operation.

In operation, the assembled tool of Fig. 3 is placed on the threaded portion of the shaft 4i, with the threads of the half-nuts 49 and 5| on the threads ofthe shaft. The nose carrying end that the threaded shaft 4| Lserves 'as a fulcrum for the tool. Downward pressure on the handle 56 of the tool, applied manually or by hanging a weight on the handle, causes the nose to be forced against the sheet metal on thedrum. The

resulting force, applied laterally to the shaft 4|, is absorbed by the bearings 44, 45, 46, and l'.

With the motor 22 driving the shaft 26 and its drum or die 2| at a desired speed, and with the motor 38 driving the threaded shaft 4| at a very slow speed, the threaded engagement of the tool and shaft causes the spinning tool to move along the shaft while the nose of the tool `is in forming contact with the sheet'metal on the drum. When the nose of the tool' reaches the opposite boundary of the sheet metal, the direction of rotation of the shaft 4| is reversed, and the tool moves back along the shaft Vtoward the point from which it originally started. It should be noted that by properly regulating the relative speeds of the drum and of the screw shaft 4|, the nose of the tool contacts the sheet metal continuously in a helicoidal path, the loops of which are very close togetherand may even overlap. Thus the sheet metal is formed into' the exact shape of the outer surface of the die 2|, and is simultaneously given an extremely smooth and highly polished surface, thus eliminating the sanding, buing, or polishing which is necessary when the spinning tool is guided by hand.

If the outer surface of the drum or die is neither frusto-conical nor cylindrical, but varies in diameter, then the operator manipulates the hand wheel 35 to vary the position of the screw with relation tothe drum surface. so that the nose 55 and its rod 52 are always kept substantially at right angles to the drum surface, as viewed from above the drum and tool.

While only one specific means (a screw shaft) for causing the tool to travel along the drum surface has been disclosed, this invention contemplates other means of accomplishing such controlled movement. For instance, the upper ange of the auxiliary frame member 29 may be longitudinally slotted, a continuously driven reversible endless chain or cleated belt arranged immediately below the slot, and the tool modified to ride in the slot and on the member 29 as a guide, removably engaging in any chain link or any cleat of the belt. In interpretation of the appended claims such modified arrangements are to be considered if the claim wording is of such breadth as to reasonably include such structure.

Having described the invention with suicient clarity to enable those familiar with the art to construct and use it, I claim:

1. In a sheet metal spinning machine of the class which includes a power rotated former or die rotatably mounted in a rigid frame, and adapted to hold a sheet metal blank to be formed, the combination with said machine of: an elongated auxiliary frame member mounted on the machine frame for pivotal movement at one end to vary its longitudinal angular relationship with the rotational axis of said die; an elongated threaded member rotatably mounted longitudinally of the auxiliary frame member; power means for rotating said threaded member at selected speeds in a selected direction; an elongated lever type blank contacting spinning tool; a half-nut having a thread complemental to that of said threaded member and rigidly mounted intermediate the ends of the tool; whereby when said tool half-nut is threadedly engaged with said threaded member it may be rocked about said threaded member as a fulcrum while being driven longitudinally therealong to operatively manipulate the spinning tool With respect to the blank on the former.

2. The organization described in claim 1 and means `for minutely moving said auxiliary frame member to vary the angular relation between the axis of rotation of the threaded member and the axis of rotation of the former.

3. The organization described in claim 1, and spaced supports on the auxiliary frame member contacting the threaded member to resist bending forces transmitted thereto by the spinning tool.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 83,998 Rais Nov. 10, 1868 157,272 Conger Dec. 1, 1874 438,407 Dewey Oct. 14, 1890 517,382 Haberman. Mar. 27, 1894 557,791 Findlay Apr. 7, 1896 FOREIGN PATENTS Number 1 Country Date 22,581 VGreat Britain of 1892 22,358 Great Britain of 1900 145,186 Germany of 1903 436,768 Great Britain or 1935 

